1 --------------------------------------------- 2 UBL image Boot Image generation using mkimage 3 --------------------------------------------- 4 5 This document describes how to set up an U-Boot image that can be directly 6 booted by a DaVinci processor via NAND boot mode, using an UBL header, 7 but without need for UBL. 8 9 For more details see section 11.2 "ARM ROM Boot Modes" of 10 http://focus.ti.com/lit/ug/sprufg5a/sprufg5a.pdf 11 12 Command syntax: 13 -------------- 14 ./tools/mkimage -l <u-boot_file> 15 to list the UBL image file details 16 17 ./tools/mkimage -T ublimage \ 18 -n <board specific configuration file> \ 19 -d <u-boot binary> <output image file> 20 21 For example, for the davinci dm365evm board: 22 ./tools/mkimage -n ./board/davinci/dm365evm/ublimage.cfg \ 23 -T ublimage \ 24 -d u-boot-nand.bin u-boot.ubl 25 26 You can generate the image directly when you compile u-boot with: 27 28 $ make u-boot.ubl 29 30 The output image can be flashed into the NAND. 31 32 Please check the DaVinci documentation for further details. 33 34 Board specific configuration file specifications: 35 ------------------------------------------------- 36 1. This file must present in the $(BOARDDIR) and the name should be 37 ublimage.cfg (since this is used in Makefile). 38 2. This file can have empty lines and lines starting with "#" as first 39 character to put comments. 40 3. This file can have configuration command lines as mentioned below, 41 any other information in this file is treated as invalid. 42 43 Configuration command line syntax: 44 --------------------------------- 45 1. Each command line must have two strings, first one command or address 46 and second one data string 47 2. Following are the valid command strings and associated data strings:- 48 Command string data string 49 -------------- ----------- 50 MODE UBL special mode, on of: 51 safe 52 Example: 53 MODE safe 54 55 ENTRY Entry point address for the user 56 bootloader (absolute address) = TEXT_BASE 57 nand_spl loader. 58 Example: 59 ENTRY 0x00000020 60 61 PAGES Number of pages (size of user bootloader 62 in number of pages) 63 Example: 64 PAGES 27 65 66 START_BLOCK Block number where user bootloader is present 67 Example: 68 START_BLOCK 5 69 70 START_PAGE Page number where user bootloader is present 71 (for RBL always 0) 72 Example: 73 START_PAGE 0 74 75 ------------------------------------------------ 76 77 Structure of the u-boot.ubl binary: 78 79 compile steps: 80 81 1) nand_spl code compile, with pad_to = (TEXT_BASE + 82 (CONFIG_SYS_NROF_PAGES_NAND_SPL * pagesize)) 83 Example: cam_enc_4xx pad_to = 0x20 + (6 * 0x800) = 0x3020 = 12320 84 -> u-boot-spl-16k.bin 85 86 !! TEXT_BASE = 0x20, as the RBL starts at 0x20 87 88 2) compile u-boot.bin ("normal" u-boot) 89 -> u-boot.bin 90 91 3) create u-boot-nand.bin = u-boot-spl-16k.bin + u-boot.bin 92 93 4) create u-boot.ubl, size = 1 page size NAND 94 create UBL header and paste it before u-boot.bin 95 96 This steps are done automagically if you do a "make all" 97 98 -> You get an u-boot.ubl binary, which you can flash 99 into your NAND. 100 101 Structure of this binary (Example for the cam_enc_4xx board with a NAND 102 page size = 0x800): 103 104 offset : 0x00000 | 0x800 | 0x3800 105 content: UBL | nand_spl | u-boot code 106 Header | code | 107 108 The NAND layout looks for example like this: 109 110 (Example for the cam_enc_4xx board with a NAND page size = 0x800, block 111 size = 0x20000 and CONFIG_SYS_NROF_UBL_HEADER 5): 112 113 offset : 0x80000 | 0xa0000 | 0xa3000 114 content: UBL | nand_spl | u-boot code 115 Header | code | 116 ^ ^ 117 ^ 0xa0000 = CONFIG_SYS_NROF_UBL_HEADER * 0x20000 118 ^ 119 0x80000 = Block 4 * 0x20000 120 121 If the cpu starts in NAND boot mode, it checks the UBL descriptor 122 starting with block 1 (page 0). When a valid UBL signature is found, 123 the corresponding block number (from 1 to 24) is written to the last 32 124 bits of ARM internal memory (0x7ffc-0x8000). This feature is provided 125 as a basic debug mechanism. If not found, it continues with block 2 126 ... last possible block is 24 127 128 If a valid UBL descriptor is found, the UBL descriptor is read and 129 processed. The descriptor gives the information required for loading 130 and control transfer to the nand_spl code. The nand_spl code is then 131 read and processed. 132 133 Once the user-specified start-up conditions are set, the RBL copies the 134 nand_spl into ARM internal RAM, starting at address 0x0000: 0020. 135 ^^^^ 136 137 The nand_spl code itself now does necessary intializations, and at least, 138 copies the u-boot code from NAND into RAM, and jumps to it ... 139 140 ------------------------------------------------ 141 Author: Heiko Schocher <hs (a] denx.de> 142
